Electronic switching system



July 9, 1957 F. AASMA ETAL ELECTRONIC SWITCHING SYSTEM Filed July 16, 1953 INVENTORS FELIX AASMA. on HANS BERTIL HAARD STIG ERIK WARRING BY: Moi 5 h ATTORNEY United States Patent 2,798,978 ELECTRONIC SWITCHING SYSTEM Felix Aasma, Lidingo, and Hans Bertil Hiifird and Stig Erik Warring, Hagersten, Sweden, assignors to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a corporation of Sweden Application July 16, 1953, Serial No. 368,474 Claims priority, application Sweden July 18, 1952 8 Claims. (Cl. 315-9) This invention relates to an arrangement for directing the electron beam of one or more trochotrons in synchronism with the stepping velocity of the electron beam of a controlling trochotron or in synchronism with a multiple of said stepping velocity.

A great many methods and means for directing the electron beam of a trochotron are known. If, however, a trochotron is desired to be used in such a manner, that the cathode of the trochotron does not emit electrons continuously but only during short time intervalsthe cathode current is pulsedthe number of possible methods for directing the electron beam of the trochotron will be quite limited. In such case the methods of directing the electron beam of the trochotron may not be used, which are based upon the principle of decreasing the potential of a contact electrode, so that the electron beam is brought to step over to the next contact electrode. Besides that it is often not desired to apply control voltages of any kind to the contact electrodes in order to be able to apply other voltages e. g. modulation voltages et cetera to them. That is made possible by this invention, according to which a control trochotron is brought to direct the electron beam of one or more controlled trochotrons in synchronistn with its own beam stepping velocity or with a multiple to said velocity. The invention is characterized by each of the control electrodes of the controlling trochotron being connected to the corresponding control electrode of the controlled trochotron or trochotrons. The electron beam of the controlling trochotron may be directed in an arbitrary known manner.

The invention will be closer described in connection with the attached drawing, where Fig. 1 shows an arrangement according to the invention, and Fig. 2 shows an embodiment of a detail of another arrangement according to the invention.

Fig. 1 shows an arrangement according to the invention. 1 is the controlling trochotron and 2 the controlled trochotron. 3 and 3 are the cathodes, 4 and 4' the control grids and 5 and 5' the anodes of the controlling and controlled rochotron respectively, 6 is a common auxiliary electrode in the controlling trochotron and 6' is the corresponding electrode in the controlled trochotron. 7, 8, 9 and are contact electrodes in the controlling trochotron and 7, 8', 9 and 10' the contact electrodes in the controlled trochotron. 11, 12, 13 and 14 are control electrodes in the controlling trochotron and 11, 12', 13' and 14' the corresponding control electrodes in the controlled trochotron. The contact electrodes of the controlling trochotron are connected together and arranged to be fed from point 19 with negative control pulses intended to make the electron beam of the controlling trochotron step from contact electrode to contact electrode. The connections of the electrodes to their respective biases have not been shown in the drawing, but if the potential of the cathode is equal to zero, the grids are usually connected to the same voltage or to a somewhat negative voltage. The auxiliary electrodes 6 and 6 are also usually connected to a voltage equal to zero or somewhat lower. The

anodes, the control electrodes and the contact electrodes are usually connected to positive biases in the order of two hundred volts. The control electrodes 11, 12, 13 and 14 of the controlling trochotron are each directly connected to the corresponding control electrodes 11, 12', 13' and 14 of the controlled trochotron and further connected to the positive bias at point 20 via resistors 15, 16, 17 and 18. A magnetical field is applied perpendicularly to the electric field.

The arrangement operates in the following manner. Suppose at first, that the electron beam of tube 1 reaches the first box, which consists of the control electrode 14 and the contact electrode 10. The part of the current, which part reaches the control electrode 14, gives rise to a voltage drop across the resistor 18, so that the control electrode 14 and by that the control electrode 14' of the trochotron 2 will have a lower potential than that of the bias at point 20 as long as the electron current of the trochotron 1 reaches said box. The contact electrodes of the controlling trochotron are connected together and arranged to be fed from point 19 with negative pulses intended to make the electron beam of the controlling trochotron step from box to box in a known manner.

Because the corresponding control electrodes of the two trochotrons are connected together the potential of the control electrodes of the trochotron 2 will also be decreased in synchronism with the potential of the corresponding control electrodes of the trochotron 1 and this independently of the cathode 3 of the trochotron 2 emitting current or not. If thus the cathode 3 of the trochotron 2 emits current continuously, this current will be directed into the boxes of this trochotron as the electron beam of the trochotron 1 reaches the corresponding boxes of that trochotron. If the cathode current of the trochotron 2 is pulsed these cathode current pulses will be directed into the boxes, which correspond to the boxes of the trochotron 1, to which the electron beam of that trochotron contemporaneously goes. The contact electrodes of the trochotron 2 are not occupied for directing the electron beam of that trochotron and may thus be utilized in a desired manner e. g. to give gate pulses to electronic devices, which are connected to them, inter alia pulse modulators or demodulators or the like. It may be advantageous to shunt the resistors 15-18, which are connected to the control electrodes, with condensers of suitable values in order to make the trochotron I operate more reliably.

Of course the principle of directing the electron beam of a trochotron by joining the control electrodes of that trochotron with the corresponding control electrodes of another trochotron is not limited only to trochotrons of the shown embodiment but may also be used with any other embodiment of a trochotron. Said principle is just as well not limited only to the method shown in connection with the figure of making the electron beam of the controlling trochotron shift from box to box. As principle any of the previously known methods of directing the electron beam of a trochotron may be used for the controlling trochotron 1.

One single trochotron may be arranged to direct the electron beam in a number of other trochotrons by joining the control electrodes of the controlling trochotron with corresponding control electrodes of all the other trochotrons.

In e. g. so called coaxial trochotrons, i. e. trochotrons with a central cathode and round this cathode located control and contact electrodes, the electron beam may suitably be brought to rotate cyclically by applying phase shifted sinusoidal voltages of the same frequency as the desired rotation frequency of the beam to the control electrodes. If both the controlling and the controlled trochotron or trochotrons are coaxial trochotrons,

the resistors 15 to 18, shown in Fig. 1, may suitably be substituted by parallel resonance circuits. These circuits are then tuned to the same frequency as the desired rotation frequency of the beam.

It is also possible to make the electron beam of the controlled trochotron or trochotrons rotate with a frequency, which is a multiple of the rotation frequency of the electron beam of the controlling trochotron. Fig. 2 shows the manner in which the control electrodes of the controlling and the controlled trochotrons respectively suitably may be connected together in such a case. 13 indicates a control electrode of the controlling trochotron and 13' the corresponding control electrode of the controlled trochotron. The control electrode 13 is connected via a resistor 17 to a positive bias 20. It is further connected to the cathode of a diode 21, the anode of which is connected to the control electrode 13'. The control electrode 13' is connected to another bias 22 via a parallel resonance circuit 23, which is tuned to the desired rotation frequency of the electron beam of the controlled trochotron. The electron beam of the controlling trochotron rotates cyclically, and if the rotation frequency is supposed to be 1, the control electrode 13 will be hit 1 times per second by said electron beam. If the circuit 23 is tuned to a harmonic of f, e. g. n.f cycles per second, the circuit will oscillate with a frequency of n. cycles per second. The current pulse from the control electrode 13 supplies energy to the circuit each nth cycle, and during the other cycles the oscillations are maintained by the electromagnetic energy stored in the circuit. Phase shifted sinusoidal voltages thus appear at the control electrodes of the controlled trochotron, the frequency of said voltages being a multiple of the rotation frequency of the electron beam in the controlling trochotron. This causes the elec' tron beam in the controlled trochotron rotate with a frequency, which is equal to said multiple of the rotation frequency of the electron beam in the controlling trochotron. If the cathode current in the controlled trochotron is continuous, the electron beam in said trochotron will hit each of the control electrodes nj times per second, so that the tuned circuits, which are connected to these electrodes, will be supplied each cycle with energy contributions from the electron beam of the controlled trochotron. The controlled trochotron will thus be mainly freerunning, if its cathode current is continuous, but each control electrode will obtain a synchronising energy contribution from the controlling trochotron each nth cycle. The biases of the control electrodes of the two trochotrons and the currents of said trochotrons ought to be chosen in such a manner as to make the arrangement operate as reliable as possible. It is thus advantageous to have a greater current in the controlling trochotron and the bias of the control electrodes of it ought to be more positive than the bias of the control electrodes of the other trochotron.

If the electron beam of the controlled trochotron is not continuous but pulsed, the energy of the tuned circuits of the controlled trochotron will be supplied mainly by the electron beam of the controlling trochotron. In such a case the controlled trochotron will operate more reliably than if the electron beam of the controlled trochotron is continuous.

In these cases too the controlling trochotron may of course control more than one trochotron.

We claim:

1. An electronic switching system comprising a control electron tube and at least one controlled electron tube, each of said tubes having a cathode means for emitting electrons forming an electron beam, a plurality of contact electrodes and a plurality of control electrodes, each of said contact electrodes being paired with a respective one of said control electrodes, and energising circuit means connected with the electrodes of the control tube for shifting the electron beam thereof from pair to pair of said paired electrodes, each of the control electrodes of the control tube being connected in circuit with a corresponding control electrode of the controlled tube for causing the electron beam of the latter tube to be shifted in synchronism with the electron beam of the control tube, the contact electrodes of the controlled tube being thus available for connection with control circuits.

2. A switching system according to claim 1 wherein resistance means are included in each circuit connection between the control electrodes of the tubes.

3. A switching system according to claim 2, wherein capacitance means are connected in shunt with said resistance means.

4. A switching system according to claim 1, wherein a network comprising inductance means and capacitance means connected in shunt with the inductance means are connected with the circuit connections between each two interconnected control electrodes of the tubes.

5. A switching system according to claim 4, wherein the said energizing circuit means are arranged to feed electron current pulses to the control electrodes of the control tube, and wherein each of said networks forms a resonance circuit tuned to a frequency equal to the pulse repetition frequency of said pulses.

6. A switching system according to claim 1 and further comprising energizing circuit means connected in circuit with the cathode means of the controlled tube for supplying the said cathode means with a continuous current.

7. An electronic switching system comprising a control electron tube and at least one controlled electron tube, each of said tubes having a cathode means for emitting electrons forming an electron beam, a plurality of contact electrodes and a-plurality of control electrodes, each of said contact electrodes being paired with a respective one of said control electrodes, and energizing circuit means connected with the electrodes of the control tube for rotating the electron beam thereof so as to shift the said beam from pair to pair of said paired electrodes, each of the control electrodes of the control tube being connected in circuit with a corresponding control electrode of the controlled tube, blocking means connected to said circuit connections between the control electrodes, the said blocking means being connected for being unblocked when the electron beam of the control tube impinges upon the respective control electrode of the said tube, and circuit means including a bias potential and a plurality of resonance networks connected in parallel with the control electrodes of the controlled tube, the said resonance networks being tuned to a selected multiple of the rotational frequency of the beam of the control tube whereby the electron beam of the controlled tube is caused to rotate with the said multiple of the rotational frequency of the electron beam of the control tube and to shift from pair to pair with the said multiple of the rotational frequency, the contact electrodes of the controlled tube being thus available for connection with control circuit means.

8. A switching system according to claim 7 and further comprising energizing circuit means connected in circuit with a cathode means of the controlled tube for supplying the said cathode means with current pulses.

References Cited in the file of this patent UNITED STATES PATENTS 2,472,200 Everhart June 7, 1949 2,563,807 Alfven et al. Aug. 14, 1951 2,565,265 Peterson Aug. 21, 1951 

